/**
 * Copyright (C) 2012 Eduard Sedov
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.es.function.impl;

import java.lang.reflect.Method;

/**
 * An implementation of {@link MethodFilter} that allows only non static methods.
 * @author ESEDO
 */
public class NonStaticPredicateMethodFilter extends StaticMethodFilter {

    /** default static instance */
    private static NonStaticPredicateMethodFilter instance = new NonStaticPredicateMethodFilter();

    /**
     * Returns the static instance of {@link NonStaticPredicateMethodFilter}.
     * @return the static instance
     */
    public static NonStaticPredicateMethodFilter get() {
        return instance;
    }

    /**
     * Throws {@link IllegalArgumentException} if the given method is static.
     * @param method the method
     * @return always {@code true}
     * @throws {@link IllegalArgumentException} if the given method is static
     */
    @Override
    public boolean accept(Method method) throws IllegalArgumentException {
        if (super.accept(method)) {
            throw new IllegalArgumentException("Only NON static methods allowed, but was " + method + ".");
        }
        return true;
    }
}
